Async OnActionExecuting in ASP.NET Core's ActionFilterAttribute
Asynchronous filters work a bit differently: first execute code that must be executed before the action, call next()
for the actual logic, finally add code to be executed after the action.
public async Task OnActionExecutionAsync(ActionExecutingContext context,
ActionExecutionDelegate next)
{
// logic before action goes here
await next(); // the actual action
// logic after the action goes here
}
The documentation is here: https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/filters#implementation